Snap lock arrangement



United States Patent Delaware Filed June 9, 1965, Ser. No. 462,683 4 Claims. (Cl. 229-45) This invention relates to a snap lock arrangement for releasably securing together adjacent telescoping inner and outer walls that are movable relative to one another in the direction of telescope, and more particularly, to a snap lock arrangement formed by curved slits of different curvature cut in the adjacent telescoping walls in a manner to intersect one another operable to interlock the walls.

This invention has its greatest utility, although it should not be limited thereto, in a carton having two telescoping walls that can be deflected transversely only a limited amount for locking or unlocking the same because of the snugly packed product within the carton. An example of this type carton is the carton commonly used for shipping a plurality of individually wrapped cream cheese packages. In such a carton, it is necessary to provide a lock arrangement that will adequately prevent the walls from telescoping. However, on the other hand, it is desirable to have a lock arrangement that is readily releasable to provide accessability to the product.

Accordingly, a basic object of this invention is to provide a positive acting lock arrangement which can be readily locked, with little lateral movement of the walls, when the walls are completely telescoped together in the manner in which the carton is to be used, and which can be readily released when desired without destroying the carton.

Another object of this invention is to provide a lock arrangement having different sized generally arcuate inter-- secting slits formed in adjacent telescoping inner and outer walls in a manner that the outer wall slit has the smaller radius of curvature and defines a convex locking element that overlaps a concave locking element adjacent the inner wall slit, which overlapped convex locking element can be biased past the inner wall locking element to interlock therewith for securing the walls together.

These and other objects will be more fully appreciated after reviewing the following specifications and accompanying drawing, wherein:

FIG. 1 is an exploded perspective view of a top cover section and bottom tray section that form a carton having the subject lock arrangement disclosed therein;

FIG. 2 is a front elevational view of the cover and tray sections closed, although the lock arrangement is shown as not being engaged;

FIG. 3 is a sectional view as seen generally from line 3-3 of FIG. 2 except with the lock arrangement shown engaged.

Note that the drawing is merely illustrative of the inventive disclosure, and thus immaterial details might be excluded from some of the figures where they are believed adequately disclosed in others.

FIG. 1 discloses in an exploded perspective view a tray and a cover 12 which cooperate with one another in the well known manner to form a carton, generally designated C and disclosed in FIGS. 2 and 3. The tray section 10 includes a central panel 14 and opposed pairs 3,337,116 Patented Aug. 22, 1967 of side walls 16 and 18. Similarly, the cover section 12 includes a central panel 20 and opposed pairs of side Walls 22 and 24. Flap extensions 26 from side walls 16 of the tray, and likewise of the cover although not shown, overlap the adjacent side walls 18 and are secured thereto in an appropriate manner to make the side walls rigid relative to one another, as is well known in the art.

The side walls 16 and 18 of the tray thus overlap and are telescoped within, respectively, the side walls 22 and 24 of the cover. In the assembled position of the carton, the walls are in a generally predetermined fixed relationship relative to one another, as is determined in the case shown, by the tray side walls 16 and 18 engaging at their upper edges the central panel 20 of the cover 12. The walls are moved relative to one another in the direction of telescope to open the carton.

The subject l'ock arrangement for releasably securing the telescoping walls together is formed by different sized slits cut in the walls. The slits are shown generally at 30 and 32 in the tray and cover respectively.

Each slit is formed with three distinct curvatures. The main or locking curvature of the slit has a rather large radius of curvature that extends from a center of curvature disposed on an axis 36 that extends in the direction of telescope of the walls to be locked. Thus, axis 36 extends generally parallel to the side walls of the tray and cover in the direction of movement, and the center of curvature of the locking curve 34 is formed generally along that axis. The second distinct curvature of the slit includes a reverse curve 40, formed tangentially at each end of the locking curvature 34, that curves throughout an angle in excess of from a center disposed on an opposite side of the locking curve center of curvature. The reverse curve radius of curvature is much smaller than the locking curve radius of curvature. The third general curvature of the slit are linear extensions 44 tangentially from the reverse curve 40 in approximate parallel relationship to one another. The free ends of the linear extensions define a plane that is tangent to or slightly spaced above the main locking curve on the side thereof remote from the locking curve center of curvature. The reverse curves 40 and linear extensions 44 are optional, although preferred, since they act mainly only to relieve the ends of the locking curve of undue strain.

Having thus described each slit, it should be noted that the slits formed in the telescoping walls of the tray and cover have diiierent proportions, and that the main locking curve 34 of the outer wall slit 32 has a smaller radius of curvature than does the corresponding main locking curve of the inner wall slit 30. Furthermore, the locking curve of the outer wall slit is formed to intersect the locking curve of the inner wall slit at two locations 46, this being accomplished by locating the center of curvatures of the outer curve a distance from the inner curve that is slightly less than the radius of curvature of the outer curve. As such, the locking curves of the inner and outer wall slits intersect one another only at two locations generally designated at 46.

The locking curves of the slits formed in the telescoping wall define generally opposed adjacent convex and concave locking elements on the opposite sides of each slit, 50 and 51 on the outer wall, and 5-2 and 53 on the inner wall. The outer wall convex locking element 50 overlaps the inner wall concave locking element 53 by a crescent shaped segment 54. Since the center of curvature of the inner and outer wall locking curves are from the same axis 36, the curves intersect at two locations 46 which are disposed on opposite sides of and substantially symmetrical of the axis. The crescent shaped segment 54 of the outer wall convex locking element 50 thus is symmetrical of the inner wall concave locking element 53.

To engage the lock arrangement, outer wall convex locking element 50* adjacent the segment 54 is deflected toward the inner wall to snap that segment past the inner wall concave locking element 53 and position the segment of the inner side of the inner wall. Thus, the convex locking element of the outer wall overlaps the concave locking element of the inner wall to abut the adjacent edges of the components at the two locations 46 of intersection of the slit. Note that any attempt to separate the telescoping walls is vigorously resisted since to so separate them, the walls must be deflected relative to one another toward and away from the interior of the carton, which deflection is resisted by the product confined within the carton. Furthermore, since the locking curves of the slits are circular and in the same direction, the points of intersection of the convex and concave locking elements must change by moving outwardly from the axis of symmetry 36. This is done by the points of intersection moving relative to both locking elements; in the direction of separation on the convex locking element of the outer wall and in the direction opposite to separation on the concave locking element of the inner wall. These changes in the points of intersection in both locking elements cause in effect a mechanical advantage working to maintain the walls together. Furthermore, the arcuate locking edges can roll relative to one another should the carton be distorted by twisting to hold the walls together even then.

To disengage the lock arrangement, the convex locking element 50 of the outer wall 24 remote from the locking edge need merely be deflected away from the inner wall operable thereby to snap the engaged crescent on the outer wall convex locking element past the inner wall to release the locking elements.

While the subject locking arrangement has been shown on a two piece carton, it has obvious use in other constructions. Accordingly, it is desired that the invention be limited only by the scope of the claims hereinafter following.

I claim:

1. In a carton having a tray and cover member, a snap lock arrangement for releasably securing together telescoping inner and outer walls of respective members disposed in adjacent back-to-back relation and movable in opposite directions relative to one another in the direction of telescope, the combination comprising:

(a) said walls having cut therethrough slits curved at different radii of curvature from centers of curvature disposed on the same side of the slits and along a common axis extended in the direction of telescope;

(b) each slit defining in its wall on its opposite sides adjacent concave and convex locking elements;

(c) the outer wall having the slit with the smaller radius of curvature and the inner wall having the slit with the larger radius of curvature;

(d) the outer wall slit intersecting the inner wall slit at two locations disposed on opposite sides of and symmetrically of said given axis, and thereby projecting a crescent shaped segment of its convex locking element between said two locations beyond the inner wall slit to overlap said segment with the inner wall concave locking element;

(e) said outer wall convex locking element adjacent the segment being deflectable, to engage the lock arrangement, toward the inner wall to snap said se ment past said inner wall concave locking element and position said segment on the inner side of the inner wall to abut, at the two locations of intersection of the slits, the adjacent edges of the outer wall convex locking element and the inner wall concave locking element.

2. A snap lock arrangement for releasably securing together telescoping inner and outer walls disposed in adjacent back-to-back relation and movable relative to one another in the direction of telescope, the combination comprising:

(a) said walls having cut therethrough intersecting slits curved at different radii of curvature from centers of curvature disposed on the same side of the slits and along a common axis extended in the direction of telescope;

(b) each slit defining in its wall on its opposite sides adjacent concave and convex locking elements;

(c) the outer wall having the slit with the smaller radius of curvature and the inner wall having the slit with the larger radius of curvature;

(d) the outer wall slit intersecting the inner wall slit at two locations disposed an opposite sides of and symmetrically of said given axis, and thereby projecting a crescent shaped segment of its convex locking element between said tWo locations beyond the inner wall slit to overlap said segment with the inner wall concave locking element;

(e) each of the opposite ends of each of said slits further communicating tangentially with a reverse curve cut in the respective wall and curving throughout on angle slightly in excess of from a center of curvature on the opposite side of the slit from the slit center of curvature and having a radius of curvature much smaller than the slit radius of curvature;

(if) said outer wall convex locking element adjacent the segment being deflectable, to engage the lock arrangement, toward the inner wall to snap said segment past said inner wall concave locking element and position said segment on the inner side of the inner wall to abut, at the two locations of intersection of the slits, the adjacent edges of the outer wall convex locking element and the inner wall concave looking element;

(g) said outer wall convex locking element, at its edge remote from segment being deflectable, to disengage, the lock arrangement, away from the inner wall to snap the engaged segment past the inner wall to release the locking elements.

3. A snap lock arrangement according to claim 2, wherein the free ends of the reverse curves each further communicates tangentially with linear extensions cut in the respective wall extending parallel to one another to the opposite ends thereof to define therebetween a plane spaced from the split on the side thereof remote from the slit center of curvature.

4. A snap lock arrangement for releasably securing together telescoping inner and outer walls disposed in adjacent back-to-back relation and movable relative to one another in the direction of telescope, the combination comprising:

(a) said walls having cut therethrough slits curved at different radii of curvature from centers of curvature disposed on the same side of the slits and along a common axis extended in the direction of telescope;

(b) each slit defining in its wall on its opposite sides adjacent concave and convex locking elements;

(c) the outer wall having the slit with the smaller radius of curvature and the inner wall having the slit with the larger radius of curvature;

(d) the outer wall slit intersecting the inner wall slit at two locations disposed on opposite sides of and symmetrically of said given axis, and thereby projecting a crescent shaped segment of its convex locking element between said two locations beyond the inner wall slit to overlap said segment with the inner wall concave locking element;

(e) each of the opposite ends of said slits further communicating with a reverse curve cut in the respective wall and extending in a direction away from the center curvature of the respective slit; (f) said outer wall convex locking element adjacent the References Cited UNITED STATES PATENTS segment being deflectable, to engage the lock arrange- 2777630 1/1957 Moberger 229 45 ment, toward the inner wall to snap said segment 5 FOREIGN PATENTS past said inner wall concave locking element and 617 306 2/1949 Great Britain position said segment on the inner side of the inner Wall to abut, at the two locations of intersection of JOSEPH LECLAIR, primary the slits, the adjacent edges of the outer wall convex locking element and the inner wall concave locking 10 PESHOCK Asslstant Examiner element. 

1. IN A CARTON HAVING A TRAY AND COVER MEMBER, A SNAP LOCK ARRANGEMENT FOR RELEASABLY SECURING TOGETHER TELESCOPING INNER AND OUTER WALLS OF RESPECTIVE MEMBERS DISPOSED IN ADJACENT BACK-TO-BACK RELATION AND MOVABLE IN OPPOSITE DIRECTIONS RELATIVE TO ONE ANOTHER IN THE DIRECTION OF TELESCOPE, THE COMBINATION COMPRISING: (A) SAID WALLS HAVING CUT THERETHROUGH SLITS CURVED AT DIFFERENT RADII OF CURVATURE FROM CENTERS OF CURVATURE DISPOSED ON THE SAME SIDE OF THE SLITS AND ALONG A COMMON AXIS EXTENDED IN THE DIRECTION OF TELESCOPE; (B) EACH SLIT DEFINING IN ITS WALL ON ITS OPPOSITE SIDES ADJACENT CONCAVE AND CONVEX LOCKING ELEMENTS; (C) THE OUTER WALL HAVING THE SLIT WITH THE SMALLER RADIUS OF CURVATURE AND THE INNER WALL HAVING THE SLIT WITH THE LARGER RADIUS OF CURVATURE; (D) THE OUTER WALL SLIT INTERSECTING THE INNER WALL SLIT AT TWO LOCATIONS DISPOSED ON OPPOSITE SIDES OF AND SYMMETRICALLY OF SAID GIVEN AXIS, AND THEREBY PROJECTING A CRESCENT SHAPED SEGMENT OF ITS CONVEX LOCKING ELEMENT BETWEEN SAID TWO LOCATIONS BEYOND THE INNER WALL OF SLIT TO OVERLAP SAID SEGMENT WITH THE INNER WALL CONCAVE LOCKING ELEMENT; (E) SAID OUTER WALL CONVEX LOCKING ELEMENT ADJACENT THE SEGMENT BEING DEFLECTABLE, TO ENGAGE THE LOCK ARRANGEMENT, TOWARD THE INNER WALL TO SNAP SAID SEGMENT PAST SAID INNER WALL CONCAVE LOCKING ELEMENT AND POSITION SAID SEGMENT ON THE INNER SIDE OF THE INNER WALL TO ABUT, AT THE TWO LOCATIONS OF INTERSECTION OF THE SLITS, THE ADJACENT EDGES OF THE OUTER WALL CONVEX LOCKING ELEMENT AND THE INNER WALL CONCAVE LOCKING ELEMENT. 